

A173280


First column of the matrix power A173279(.,.)^j in the limit j>infinity.


3



1, 1, 3, 7, 29, 129, 757, 5185, 41155, 368351, 3671635, 40295943, 482758111, 6268066531, 87668492115, 1314023850727, 21011431917453, 357014074280785, 6423561495057421, 122004755658629081, 2439367774898883497, 51213663674167659301, 1126452985959434543237
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OFFSET

0,3


COMMENTS

We can generalize A173279 to other matrices derived from some sequence S by Smat(n,k) := S(nr*k), r >= 2,
and find that they define sequences B(x) via S(x)= B(X)/B(x^r), b(n) = Sum_{t=0..n, nt == 0 (mod r)} S(t)*B_{(nt)/r}.
The sequence here is the case of S=A000142 and r=2.


LINKS

Table of n, a(n) for n=0..22.


FORMULA

A000142(x) = A(x)/A(x^2), where A(x) and A000142(x) are the o.g.f.'s associated with A000142 and this sequence here.
Sum_{n>=0} 1/a(n) = 2.519966353393413186683398448854995831308...
a(n) = (A173279^j)(n,0).
a(n) = Sum_{t=0..n, nt even} t!*a_{(nt)/2}.  R. J. Mathar, Feb 22 2010


MAPLE

A173280 := proc(n) option remember; local a, l; if n = 0 then 1; else a :=0 ; for l from n to 0 by 2 do a := a+ l!*procname((nl)/2) : end do ; a ; end if; end proc:
seq(A173280(n), n=0..60) ; # R. J. Mathar, Feb 22 2010


CROSSREFS

Cf. A000142.
Sequence in context: A358389 A358279 A217576 * A141477 A211371 A302157
Adjacent sequences: A173277 A173278 A173279 * A173281 A173282 A173283


KEYWORD

nonn


AUTHOR

Gary W. Adamson, Feb 14 2010


EXTENSIONS

Extended, and invalid comment on convergence to e removed, by R. J. Mathar, Feb 22 2010
Index of B in the convolution formula in the comment corrected by R. J. Mathar, Mar 23 2010


STATUS

approved



